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# CMMetadataDataTypeRegistryRegisterDataType(_:description:conformingDataTypes:)

Register a data type with the data type registry.

```
func CMMetadataDataTypeRegistryRegisterDataType(_ dataType: CFString, description: CFString, conformingDataTypes: CFArray) -> OSStatus
```

## Parameters

`dataType`

Identifier of data type being registered.

`description`

Human-readable description of data type being registered (for aiding debugging operations).

`conformingDataTypes`

Data types that this data type conforms to.

## Return Value

If successful, a nonzero result code. See [Metadata Registry Error Codes](/documentation/CoreMedia/metadata-registry-errors).

## Discussion

This routine is called by clients to register a data type with the data type registry. The list of conforming data type identifiers must include a base data type. If the data type has already been registered, then it is not considered an error to re-register it as long as the list of conforming data type identifiers has the same entries as the original; otherwise an error will be returned.

---

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